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  • Articles: DFG German National Licenses  (6)
  • 1980-1984  (6)
Source
  • Articles: DFG German National Licenses  (6)
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Microbial uptake of dissolved organic matter in Mcmurdo Sound, Antarctica (1981)
    Springer
    Marine biology 61 (1981), S. 89-94 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution and activity of bacterioplankton, and the turnover of dissolved organic matter (DOM) were examined in McMurdo Sound, Antarctica. On the eastern side of the Sound, bacteria averaged 6.5×108 l-1, and turnover rates of dissolved adenosine triphosphate, D-glucose and l-leucine averaged 16, 116 and 124 h, respecitvely. These molecules as well as thymidine were taken up maximally from 0° to 5°C and near-maximally from -1.5° to 0°C, indicating bacterial adaptation to rapid turnover of dissolved organic matter at the ambient temperature. On the west side of the Sound, bacteria averaged only 0.65×108 l-1, and turnover times for adenosine triphosphate, D-glucose and lleucine averaged 59, 20454, and 3070 h, respectively. Total microbial adenosine triphosphate (an indicator of total microbial biomass) and chlorophyll a were also much lower at the western than at the eastern side stations. Moreover, no primary production could be detected at one western side station (New Harbor). Thus, in McMurdo Sound, the western side is highly oligotrophic, but the eastern side has an abundant active bacterioplankton, comparable to that of temperate coastal waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386648
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    High-affinity uptake of an ammonium analogue by two marine microflagellates from the oligotrophic Pacific (1983)
    Springer
    Marine biology 74 (1983), S. 161-168 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two marine microflagellates, isolated from the North Pacific Central Gyre, and tentatively identified as Platymonas sp. and Mantoniella sp., were examined for uptake of 14C-methylamine, a non-metabolizable analogue of ammonium. Half-saturation constants (K m) for ammonium transport, estimated from competitive inhibition of methylamine transport by ammonium, were 50 nM for Platymonas sp. and 2.9 nM for Mantoniella sp. These values are the lowest so far reported, indicating that the transport systems are well adapted to extremely low ammonium environments. The ratio of the K m for methylamine to the K m for ammonium was 17 for Platymonas sp. and 41 for Mantoniella sp. The observed ratios fell within the relatively narrow range reported for various organisms, including bacteria, fungi and phytoplankton (25.0±15.5, $$\bar x$$ ± SD, n=9), although the reported K mvalues for both ammonium and methylamine vary over a thousand-fold range. The use of 14C-methylamine may therefore be a promising technique for studying the kinetics of ammonium transport by marine microorganisms, particularly those in oligotrophic environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413919
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Renal plasma clearance: A valuable marker in myelomatosis (1982)
    Springer
    Annals of hematology 45 (1982), S. 1-11 
    Details
    ISSN: 1432-0584
    Keywords: Bence Jones proteinuria ; Glomerular filtration rate ; Myelomatosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Forty-two consecutive patients with untreated myelomatosis (MM) formed the basis of settling the validity of measuring the renal plasma clearance (RPC), either indirectly using the serum creatinine or directly using the glomerular filtration rate (GFR) when studying anaemia, calcium metabolism, proteins in serum and urine, and prognosis. Patients without light chain excretion in the urine had a higher GFR (P〈0.01) than patients with light chain excretion. The haemoglobin concentration (Hb) was strongly correlated (P〈0.001) to both, serum creatinine and GFR. Patients with normal serum concentrations of the physiological immunoglobulins had higher Hb (P〈0.01) than patients with reduced serum immunoglobulins. Patients with serum calcium 〉3.00 mmol/l had additional reduced GFR compared with the other myeloma patients. The serum parathyroid hormone was decreased (P〈0.01) and inversely correlated to the GFR. Patients with increased serum creatinine, reduced GFR or with osteolytic bone lesions had a decreased survival rate. The study shows that the major factor in prediction of Hb and prognosis in patients with MM is the RPC expressed either as the serum creatinine or the GFR. In addition, the significant correlations between the GFR and the other variables in MM assessed the RPC to be a useful and valuable marker in studies of anaemia, protein and calcium metabolism and prognosis in MM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320493
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of temperature on rate of photosynthesis in Antarctic phytoplankton (1982)
    Springer
    Polar biology 1 (1982), S. 33-38 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The rate of photosynthesis of marine antarctic phytoplankton (western Scotia Sea and Bransfield Strait) was determined as a function of temperature, from ambient (-0.8°C to 1.0°C) to 28°C. Photosynthetic rates, based on radiocarbon incorporation during half-day incubations, were increased by as much as 2x with temperatures up to 7°C; at higher temperatures the rates decreased rapidly, so that at 28°C the rates were only 3% of that at ambient temperatures. In antarctic surface waters during the austral summer the rate of photosynthesis by phytoplankton thus is limited by thermodynamic effects on metabolic reactions, in spite of high nutrient concentrations and saturating light levels. The observed rates were in agreement with thermodynamic models of the dependence of phytoplankton growth rate on temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568752
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  • 5
    Electronic Resource
    Electronic Resource
    Nitrogen assimilation by phytoplankton in the Scotia Sea (1983)
    Springer
    Polar biology 2 (1983), S. 137-147 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study of nitrogen metabolism of phytoplankton was one component of a large multidisciplinary program designed to examine the biological productivity of the eastern Scotia Sea, Antarctica, with regard to the importance of the zone of mixing of the northern outflow of the Weddell Sea with Drake Passage waters. The total integrated N-uptake for the euphotic zone in the southwest part of the Scotia Sea was estimated to be in the range of 9.7–14.1 mmol N·m-2·d-1, while for the eastern part of the Scotia Sea it was less than half of this, being 2.1 to 4.7 mmol N·m-2·d-1. The rate of primary production could not be correlated with the front between the two major water masses. Assimilation rates of 15N-enriched substrates indicate that phytoplankton production in the Scotia Sea during austral summer subsists predominantly on ammonia (85%), with lower incorporation rates for nitrate (14%) and nitrite (1%). Nitrate assimilation was much more light-dependent than the uptake of ammonia. These data indicate that there is a rapid and extensive mineralization of organic matter in the surface waters, resulting in a recycling of nitrogen approximately eight times before it is lost from the euphotic zone. This has important implications with regard to the dynamics of the microbial food web in antarctic waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00448963
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Vanadate interaction with the Na, K-ATPase an assay of serum vanadate based on the displacement of (48V) vanadate from Na, K-ATPase (1980)
    Springer
    Basic research in cardiology 75 (1980), S. 455-459 
    Details
    ISSN: 1435-1803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die [48V]Vanadatbindung an die (Na++K+)-ATPase wurde unter Äquilibriumbedingungen und bei optimalen Inkubationsbedingungen gemessen. Scatchard-Analysen der Vanadatbindung ergeben eine identische Bindungskapazität für Vanadat und Ouabain (g-Strophanthin) in angereicherten (Na++K+)-ATPase-Präparationen. Mit Hilfe dieser hochaffinen Vanadatbindung an die (Na++K+)-ATPase ist eine Bestimmungsmethode für Vanadat im Serum möglich, die sich das Prinzip des „Radiorezeptor-Assays” zunutze macht. Außerdem wird experimentell nachgewiesen, daß die [3H]Ouabain-Bindung an die (Na++K+)-ATPase in Gegenwart von Vanadat zu einem Enzym-Vanadat-Ouabain-Komplex führt, in dem Vanadat relativ fest gebunden wird.
    Notes: Summary Under optimum conditions for vanadate binding to Na, K-ATPase equilibrium binding data for a range of vanadate concentrations were compiled. Scatchard plots indicated an identical binding capacity for vanadate and ouabain with conventionally prepared Na, K-ATPase batches. A method for determination of vanadate in serum based upon the high affinity of vanadate for Na, K-ATPase is described. The method takes advantage of the shift in equilibrium binding of (48V) vanadate upon addition of an aliquot of vanadate-containing serum. It is shown that the interplay between vanadate and ouabain in vanadate-facilitated oubain binding to Na, K-ATPase leads to an enzyme-vanadate-ouabain complex to which vanadate is rather firmly bound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01908411
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    Paper (German National Licenses)
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